The invention relates to circuit arrangement which is intended in particular for use in a variable rotation speed wind energy installation, comprising a double-fed asynchronous generator, an additional resistor and a converter; and methods hereof.
Circuit arrangements such as these which are intended for use in variable speed wind energy installations are widely used in practice and are thus prior art by virtue of obvious prior use. However, it has been found to be disadvantageous when using double-fed asynchronous machines (DASM) that these are disconnected from the network in the event of a network short circuit at the medium-voltage level. This means that it is not possible to achieve the desired network stabilization by means of a wind power installation which is operated with a double-fed asynchronous machine.
In the past, the necessary network stabilization has thus been achieved by the network operators by means of conventional power stations. Owing to the rapidly increasing number of wind power installations and the rapidly rising power level associated with them, which has now reached the magnitude of conventional power stations, the requirements for wind power installations must, however, be matched to those of conventional power stations. In particular, permanent network coupling is being increasingly demanded in order that the wind energy installation can set up the network again, and can stabilize it, once a medium-voltage network short circuit has ended.